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Enable setting up MTU #156

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Enable setting up MTU #156

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31 changes: 27 additions & 4 deletions src/net.c
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Original file line number Diff line number Diff line change
Expand Up @@ -260,7 +260,7 @@ static int rtnl_talk(struct rtnl_handle *rtnl,
return 0;
}

static int hyper_up_nic(struct rtnl_handle *rth, int ifindex)
static int hyper_up_nic(struct rtnl_handle *rth, int ifindex, unsigned int mtu)
{
struct {
struct nlmsghdr n;
Expand All @@ -277,6 +277,22 @@ static int hyper_up_nic(struct rtnl_handle *rth, int ifindex)
req.i.ifi_flags |= IFF_UP;
req.i.ifi_index = ifindex;


// As per Wiki:
// https://en.wikipedia.org/wiki/Maximum_transmission_unit#Table_of_MTUs_of_common_media
//
// The minimum and maximum value of MTU is (68, 2^32-1)
if (mtu < 68 || mtu > 4294967295)
mtu = 1500;

// creating a rtnetlink message to set the MTU of the device
struct rtattr *rta;
rta = (struct rtattr *)(((char *) &req) + NLMSG_ALIGN(req.n.nlmsg_len));
rta->rta_type = IFLA_MTU;
rta->rta_len = RTA_LENGTH(sizeof(unsigned int));
req.n.nlmsg_len = NLMSG_ALIGN(req.n.nlmsg_len) + RTA_LENGTH(sizeof(mtu));
memcpy(RTA_DATA(rta), &mtu, sizeof(mtu));

if (rtnl_talk(rth, &req.n, 0, 0, NULL) < 0)
return -1;

Expand Down Expand Up @@ -567,8 +583,15 @@ static int hyper_setup_interface(struct rtnl_handle *rth,
char buf[256];
} req;

// TODO(HuKeping): We don't check the value of mtu here because
// the external caller may not set the MTU. In the meantime, we could
// set it to 1500 as default if it was not provided.
//
// Feel free to dissucss about it if anybody think we should ask for the
// MTU value here.
if (!(iface->device && iface->ipaddr && iface->mask)) {
fprintf(stderr, "interface information incorrect\n");
fprintf(stderr, "interface information for setting up is incorrect, device:%s,ipaddr:%s,mask:%s\n",
iface->device, iface->ipaddr, iface->mask);
return -1;
}

Expand Down Expand Up @@ -604,7 +627,7 @@ static int hyper_setup_interface(struct rtnl_handle *rth,
return -1;
}

if (hyper_up_nic(rth, iface->ifindex) < 0) {
if (hyper_up_nic(rth, iface->ifindex, iface->mtu) < 0) {
fprintf(stderr, "up device %d failed\n", iface->ifindex);
return -1;
}
Expand Down Expand Up @@ -719,7 +742,7 @@ int hyper_setup_network(struct hyper_pod *pod)
}
}

ret = hyper_up_nic(&rth, 1);
ret = hyper_up_nic(&rth, 1, 1500);
if (ret < 0) {
fprintf(stderr, "link up lo device failed\n");
goto out;
Expand Down
1 change: 1 addition & 0 deletions src/net.h
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Original file line number Diff line number Diff line change
Expand Up @@ -31,6 +31,7 @@ struct hyper_interface {
int ifindex;
char *ipaddr;
char *mask;
unsigned int mtu;
};

struct hyper_route {
Expand Down
3 changes: 3 additions & 0 deletions src/parse.c
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Original file line number Diff line number Diff line change
Expand Up @@ -776,6 +776,9 @@ static int hyper_parse_interface(struct hyper_interface *iface,
} else if (json_token_streq(json, &toks[i], "netMask")) {
iface->mask = (json_token_str(json, &toks[++i]));
fprintf(stdout, "net mask is %s\n", iface->mask);
} else if (json_token_streq(json, &toks[i], "mtu")) {
iface->mtu = (json_token_int(json, &toks[++i]));
fprintf(stdout, "net mtu is %u\n", iface->mtu);
} else {
fprintf(stderr, "get unknown section %s in interfaces\n",
json_token_str(json, &toks[i]));
Expand Down